The present invention relates to an electrically operated valve, in particular of the type used in a hydraulic unit mounted in a motor vehicle.
The invention also relates to a process for fitting a solenoid on the electrically operated valve, and a process for removing the solenoid from the electrically operated valve.
These electrically operated valves generally include a substantially cylindrical housing provided with a collar forming a stop for a solenoid which is mounted at one of the ends of the electrically operated valve. The solenoid is provided with an axial hole receiving this end of the electrically operated valve when these two elements are assembled. The solenoid can thus be axially displaced along this end to abut against this collar. The electrically operated valve also includes first connecting means of the housing to the solenoid when it is in abutment against the collar, and second connecting means of the housing to the inside of a hole forming a port in the hydraulic unit.
The invention relates in particular to these first connecting means which simultaneously form means for axial locking of the solenoid in its service position on the valve housing. The electrically operated valve as such will not be described in detail since it is well known to the man skilled in the art. First and second connecting means associated with the housing of an electrically operated valve are known. Two embodiments generally used are illustrated in FIGS. 1, 2 respectively.
In FIG. 1 which shows very diagrammatically an electrically operated valve of the type described in the document EP 0 538 986. The electrically operated valve 1 is shown in its installed position in a hydraulic unit 2. The details of the inside of the valve are not shown, since they do not directly relate to the invention. The electrically operated valve 1 includes a substantially cylindrical housing 3 one (4) of the ends of which is shown in FIG. 1. A solenoid 5 includes a through axial hole 6 receiving the end 4 of the electrically operated valve 1. The solenoid 5 is in abutment against a collar 7 provided on the periphery of the housing 3 and is locked there in a service position by means of axial locking means.
In the example shown in FIG. 1, these means for axially locking the solenoid 5 include a thread 8 at the tip of the end 4 of the housing 3 which co-operates with a nut 9 screwed onto the end 4 and tightened against an end surface of the solenoid so as to bias the end surface opposite to this against the collar 7. The thread 8, with the tapping of the nut 9, forms the first connecting means to connect these two elements together.
The housing 3 is provided over a part of its length with a second thread 23 which co-operates with a tapping 24 provided in a hole forming a port 25 in the hydraulic unit 2. The thread 23, with the tapping 24, forms second connecting means to connect the electrically operated valve 1 to the hydraulic unit 2. The collar 7 has a hexagonal shape in order to allow screwing of the electrically operated valve 1 into the hydraulic unit by means of a tool (not shown).
In the example shown in FIG. 1, a first sealing ring 26 is arranged in a conical cavity 27 around the opening of the hole forming a port 25 on the face of the hydraulic unit 2. A second sealing ring 28 and a third sealing ring 29 are arranged in a groove 30, 31 respectively on the periphery of the housing 3 of the electrically operated valve 1.
FIG. 2 shows an electrically operated valve 1 which differs from that described with reference to FIG. 1 only by the fact that it includes another type of means for connecting or axially locking the solenoid 5 relative to the housing 3 of the electrically operated valve 1. The other elements being the same, they have retained their reference numbers and will not be described further.
The axial locking means shown in FIG. 2 include a flange 10 at one of the ends of the solenoid, this flange being provided with a plurality of through holes 11 receiving a respective fixing screw 12 which can be screwed into a respective tapped hole 13 provided in the hydraulic unit. The flange 10 is thus tightened against the hydraulic unit, biasing the solenoid 5 against the collar 7 of the valve housing 3.
Instead of the flange, lugs could also be used provided with a hole in place of the flange 10. These lugs could be four in number and uniformly spaced around the periphery of the solenoid 5.
However, these known solutions, in particular for these first connecting means, are bulky and costly to use. Moreover, they require anti-corrosion treatment of the part of the electrically operated valve which is exposed to the environment.